3 VS 4

So I'm learning how to play with four fingers (pinky included) and I'm switching over my licks that I played with three fingers (pent box etc) to playing them with four fingers, ...as well as learning all the techniques involved with four finger playing (shred and such).

Does anybody switch back to playing the blues/pent box riffs with 3 fingers? I know (... I forget his name, from Dream Theatre...) does from watching his videos. I can't see how that'd be economical to be switching back and forth between scales (playing with 4 fingers) and pent box riffs (played with 3 fingers). Maybe people just don't switch back and forth. I do. .....using 4 fingers all the time though.

(ie. does anybody use both 3 finger riffs and 4 finger riffs (blues riffs and 80s riffs, respectively) in their soloing and why not just play everything with 4 fingers.)

It all boils down to comfort. Sometimes you only need 3 fingers. There's no use of throwing in an extra finger if it's not needed.

Sometimes I use 3 fingers on some licks, sometimes I use 4, all depends on the lick, the stretch, how many notes.....blah blah.

Just do what's comfortable.

Dream Theater guitarist = John Petrucci

If you're still having problems, just post some licks, I'll/Others will tell you how we play them.

I use both ... 3 fingers for pentatonics and some higher fret stuff , but generally it's all four fingers.

The fourth finger being shorter it is often easier, when using multiple fingers - as you might prefer to do for a bend of a tone or more - just to use the 3 longer fingers when you're bending. The tendons of 3rd and 4th are such that they are not totally independant, even the great pianist Chopin bemoaned that his little fingers wouldn't obey him.
Personally I use my pinky a lot but rarely for bending.